
lonne |
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Derek Vande Brake wrote:
Does 4d6 drop the lowest correspond to a 15 point buy or a 20 point buy? What about 5d6 drop the lowest two? 2d6+6 - the "Heroic" method from the PRD?
The standard method (4d6, discard lowest die) gives results that would on average cost 19,46 ability score points if you treat results in the range 3-7 as costing -4 points. If you instead reroll results less than 7, the average cost is 20,70 points. In either case, this is pretty close to a 20 point buy.
To check this, first work out that of the 1296 different outcomes of 4d6, the number of outcomes that give a result of 3, 4, 5, ..., 16, 17 and 18 are 1, 4, 10, 21, 38, 62, 91, 122, 148, 167, 172, 160, 131, 94, 54 and 21, respectively. Then do the sums.